The intensive rebuilding of the ecosystems including the gradual extinction of the reef communities which is observed in the late Frasnian and early Famennian ages corresponds to the large restriction of the shelf areas as well as to the increase of humidity. While the nearshore areas were often uplifted and/or destroyed, as concerned their previous stable ecosystem, the frontal margin of the reefoid communities progressed deeper basinwards with some ingressions and consequent replacement by the basinal, both pelagic and benthic communities. The terrigenous phyto-debris, oogonies of Charophyta, fish remains and other indications of rising climatic humidity are noticed from Moravian shelfs.